(I had been posting in another thread, but I kept getting error messages when I tried to add another reply. As such, I'm seeing if a new thread will take my submission.)
We are thinking of adding insulation to our old home in Fort Worth, Texas. There's a subsidy program where the state pays for part of the insulation if you use a participating vendor.
Here are the price breakdowns for blown-in fiberglass*:
R-30 (12 inches) - $200 R-38 (17 inches) - $460 R-49 (18.5 inches) - $709
*I don't know any more about the composition of the fiberglass, other than it's blown-in, it's white, it's non-itchy, and it's very lightweight.The 1,000 sq. foot house is 80+ years old with maybe a couple of inches of old cellulose in the attic. The attic is completely "open".
There's a gas furnace in the attic and a new electric A/C unit (14 SEER) outside. We're more concerned about insulating for the heat vs. the cold.
What's the best deal? (I've used online savings calculators--but they don't seem to give consistent answers.)
Maybe I'm a little confused on R-values. Is the value # determined by how many inches you have blown-in? In other words, 12 inches provides R-30 protection. I couldn't have 12 inches of R-38... I'd need more inches to get the stronger R-value, right?
Or is the R-value an inherent quality of the fiberglass (like the SPF value of sunscreen) where a higher R-value equals more "protection"? In other words, 18.5 inches of R-49 is greater than 18.5 inches of R-30.
Thanks again for everyone's help. I think I'm eventually going to understand all this -- but you've got to start somewhere, right? :)
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